Rhodamine labeled cellulose nanocrystals as selective “naked-eye” colorimetric and fluorescence sensor for Hg2+ in aqueous solutions

Abstract

Novel rhodamine-based fluorescence cellulose nanocrystals (RhB-CNCs) were synthesized and investigated as an effective naked-eye colorimetric and fluorescent sensor for detection of Hg2+ in aqueous solutions. RhB-CNCs were characterized by using FT-IR, XRD, XPS, TEM, AFM, ζ-potential measurements, dynamic laser light scattering (DLS), UV–vis absorption and fluorescence spectroscopy. The average dimension of RhB-CNCs was about 18–20 nm in width and 160–180 nm in length, which could be stably dispersed in aqueous solutions. RhB-CNCs were able to selectively recognize Hg2+ by “naked-eye” and spectroscopic method in aqueous solutions. The fluorescent and colorimetric detection limits were determined to be 232 nM and 746 nM, respectively. This sensor could function in the pH range of 3–12 and exhibited excellent interference immunity. By means of Benesi–Hildebrand plot, 1:1 binding stoichiometry was obtained, and the binding constant between RhB-CNCs and Hg2+ was found to be 4.15 × 105 M−1. The fluorescent-labeled CNCs can be readily used for selective and sensitive detection of Hg2+ in aqueous media and exhibit great potential applications for chemosening, bioimaging and sewage treatment. Novel rhodamine-based fluorescence cellulose nanocrystals were prepared and used as an effective naked-eye colorimetric and fluorescent sensor for detection of Hg2+ in aqueous solutions.